Switch with two contact pairs



5 w. A. DE SMIDT 3,396,255

SWITCH WITH TWO CONTACT PAIRS Filed Dec. 16. 1966 1&9.

INVENTOR WOODROW A. DE smor ATTORNEY United States Patent 3,396,255SWITCH WITH TWO CONTACT PAIRS Woodrow A. De Smidt, Whitefish Bay, Wis.,assignor to Allen-Bradley Company, Milwaukee, Wis., 21 corporation ofWisconsin Filed Dec. 16, 1966, Ser. No. 602,394 Claims. (Cl. 200-153)ABSTRACT OF THE DISCLOSURE This disclosure relates to a switchincluding/a case with two terminals at opposite lower corners. Tworesilient leaves extend upwardly from the terminals and turn inwardly todefine parallel, vertically spaced contact portions that are biasedtogether and that each bear two contacts to have two spaced pairs ofcontacts. An actuating arm is pivotally mounted in the case at its innerend and carries a bar shaped cam which extends between the leavesbetween the contact pairs. The cam pivots with the arm between a firstposition where it spreads the contact portions to open both contactpairs and a second position where it is disengaged to allow both contactpairs to close. The arm extends above the case and is mechanicallyoperable to be pivoted toward one of said positions, and a bias springoperates between an abutment on the case and the arm to urge the armtoward the other of said positions.

Background of the invention (1) Field.This invention pertains to amechanically operable resilient leaf switch construction useful inauxiliary switches, relays and the like which includes two pairs ofcontacts for enhanced reliability.

(2) Prior art.A variety of mechanically operable resilient leaf switchconstructions are known. These usually involve a single pair of contactsat least one of which is carried on a resilient leaf, the resilience ofthe leaf serving to bias the contacts toward either a normally open or anormally closed position. A plunger or other mechanical actuator is usedto overcome the resilience of the leaf and close or open the contacts asthe case may be, and upon disengagement of the actuator the resilientleaf causes the contacts to assume their original positions. Suchswitches are quite advantageous from the standpoint of simplicity andcost, but they are not particularly reliable, especially insofar as thecontact action in one direction depends only upon the resilience of theleaf. A slight loss of resilience as the result of long usage can, forexample, easily prevent proper contact operation. Further, dust or dirtmay relatively easily prevent proper closing of the single pair ofcontacts.

Summary of the invention This invention contemplates a mechanicallyoperable resilient leaf switch construction including two resilient leafportions presenting two spaced pairs of contacts that are normallybiased toward one another by virtue of the resilience of the leaves. Thecontacts may be opened mechanically by virtue of a cam carried by anactuating arm. Upon disengagement of the cam, the leaves move togetherand the two spaced pairs of contacts in effect insure that there will beadequate contact. That is, at least one pair of contacts is virtuallycertain to make effective electrical contact insuring a completedcircuit through the switch. It is the object of this invention toprovide a switch construction of this type which is highly effective butrelatively simple and inexpensive, and which is easily convertiblebetween normally open and normally closed types of operation.

3,396,255 Patented Aug. 6, 1968 Brief description of the drawings Theattached drawing, which comprises a part hereof, shows three preferredembodiments of the invention, as follows:

FIG. 1 is an exploded view in perspective of a switch constituting oneembodiment of the invention,

FIG. 2 is a front view in elevation of the embodiment of FIG. 1 (thecover portion of a case for the switch being removed to show theinterior parts) showing the switch in open condition.

FIG. 3 is a view similar to FIG. 2, but showing the switch in closedcondition.

FIG. 4 is a view similar to FIGS. 2 and 3 but showing a secondembodiment of the invention, and

FIG. 5 is a view similar to FIGS. 2-4 but showing a third embodiment ofthe invention.

Description of the preferred embodiments The embodiment of the inventionshown in FIGS. l-3 includes an insulating case designated generally bythe reference numeral 1. The case 1 is preferably of a splitconstruction comprising a rear portion or base 2 and a front portion orcover 3, the cover 3 being omitted in FIGS. 2-5 to show the internalparts. The base 2 and cover 3 are provided with mating central bosses 4at their bottom edges, and a pin or rivet 5 extends through the bosses 4to hold the case portions 2 and 3 together.

A pair of U-shaped terminals 6, provided with terminal screws 7, aremounted at and extend outwardly through the bottom of the case 1 at itslower corners, the terminals 6 being provided with locating notches 8which receive projections 9 formed in the case 1 to orient and hold theterminals 6 in place.

A pair of leaves 10, formed of strips of suitable resilient,electrically conductive material, have their lower ends fixed torespective terminals 6. The leaves 10 extend upwardly and then turninwardly at right angles and extend across the case 1 to present anddefine horizontal, vertically spaced contact portions 11 which terminateat free ends on opposite sides of the case 1. The leaves 10 are shapedso that the contact portions 11 are resiliently biased toward oneanother. The two portions 11 each carry a left contact 12 and a rightcontact 13, the contacts 12, 13 being in alignment to present twohorizontally spaced pairs of contacts, the members of both pairs beingnormally biased toward one another by virtue of the resilient bias ofthe portions 11. Between the contact pairs 12, 13 the portions 11 areoffset apart at 14.

An inverted triangular well is formed at the upper central portion ofthe base 2 which receives an actuating arm 16, the arm 16 beingpivotally mounted at its inner end by means of a trunnion 17 which isrot-atably received in an opening 18 in the rear wall of the well 15.Extending forwardly from the inner end of the arm 16 is a cam 19 whichis formed integrally therewith and which extends between the contactportions 11 and between the contact pairs 12, 13, being received in thespace provided by the offsets 14. The cam 19 pivots coaxially with thearm 16 and is provided with a trunnion 20 which is rotatably received inan opening 21 in the cover 3 to complete the pivotal mounting of the arm16. The cam 19 is substantially bar shaped and its pivotal axis is atits midpoint.

The base 2 is further provided with an upstanding abutment 22 whichseats a compression spring or bias means 23 which bears against the arm16 to urge it to pivot in a counterclockwise direction as seen in FIGS.2 and 3.

The spring 23 is of suflicient strength to overcome the resilience ofthe leaf portions 11 and normally holds the arm 16 in thecounterclockwise position shown in FIG. 2 where it is against the lefthand edge of the well 15. In this position, the bar cam 19 is transverseto the contact portions 11 and its ends have engaged and spread theportions 11 apart to open both contact pairs 12, 13. The arm 16 can,however, be mechanically engaged by a suitable operator, indicated as 24in FIG. 3, to be pivoted in a clockwise direction to the position ofFIG. 3 in which the spring 23 is compressed and the arm 16 is againstthe right hand edge of the well 15. In this position, the cam 19 is in ahorizontal position where it is parallel to and in effect disengagedfrom the portions 11, the resilience of the portions 11 then causingboth contact pairs 12, 13 to close. It will be obvious that the operator24 may be of any suitable type depending upon the appliaction to whichthe switch is put. It might, for example, be the armature of a contactoror the plunger of a solenoid. Under some circumstances, the arm 16 mayeven be pivoted manually. pon release of the force exerted by theoperator 24, the spring 23 will cause the arm 16 to move back to theposition of FIG. 2, thus opening the contact pairs 12, 13.

The two pairs of contacts 12, 13 insure that there will be in effectiveelectrical circuit through the switch even when the contact portions 11may have lost some resilience or be slightly out of line, or where theremay be dust or dirt present, it being virtually certain that at leastone pair will make good electrical contact. In addition to insuringclosing, however, the construction shown insures effective opening ofthe contact pairs 12, 13. It will be noted that as the cam 19 pivotswith the arm 16 its ends will engage both contact portions 11 and causethem to be spread or flexed in opposite directions about their fixedends, the ends where the leaves 10 turn at right angles to lead to theterminals 6. Since the fixed and free ends of the two portions 11 are opposite, they always remain substantially parallel, insuring that bothcontact pairs 12, 13 will be opened and will open at substantially thesame time.

The flexibility of the portions 11 provides a slight wiping action whichis helpful in insuring good electrical contact between the contacts 12,13. This effect is enhanced in the embodiments shown by the verticalportions of the leaves 10 which also flex slightly during opening andclosing. Although this configuration is preferred, however, the leaves10 need not necessarily be angled as shown and the portions 11 could,for example, lead directly laterally outwardly to terminals on oppositesides of the case 1.

The embodiment of the invention shown in FIGS. 1-3 has a normally opentype of operation in that the contact pairs 12, 13 are normally heldapart by the action of the spring 23. The embodiment shown in FIG. 4 issubstantially the same, but provides a normally closed operation. InFIG. 4, the same reference numerals have been used to designate theseveral elements with the exception of the actuating arm and cam. Inthis embodiment there is an actuating arm 25 which carries a cam 26,both of which are quite similar to the arm 16 and cam 19 except that theradial orientation of the cam 26 with respect to the arm 25 is such thatwhen the arm 25 is in the position shown in FIG. 4, where it is normallyheld by the spring 23, the cam 26 is parallel to and disengaged from theportions 11 and the contact pairs 12, 13 closed. Mechanical pivoting ofthe arm 25 to the right or clockwise against the spring 23 will causethe cam 26 to open the contact pairs 12, 13.

The embodiment of the invention shown in FIG. is also essentially thesame as that shown in FIGS. 1-3 and the same reference numerals havebeen used throughout to designate the several elements. In theembodiment of FIG. 5, however, there is a second upstanding abutment 27on the base 2 on the opposite side of the arm 16, and the spring 23 isshown as operating between this second abutment 27 and the arm 16. Withthe spring 23 on this side of the arm 16, the switch is normally in theposition of FIG. 5 to give it a normally closed type of operation.Moving the spring 23 so that it operates between the arm 16 and theabutment 22, as shown in FIGS. 2 and 3, will, however, easily convertthe switch to a normally open type of operation like that shown in FIGS.1-3.

Although three preferred embodiemnts of the invention have been shownand described, it will be obvious that various modifications might bemade without departure from the invention. It is not intended that theinvention be limited by the showing herein or in any other manner exceptinsofar as limitations appear specifically in the following claims.

I claim:

1. A switch comprising: a case; a pair of terminals mounted in the case;a pair of leaves mounted in the case and connected to respectiveterminals and presenting parallel facing elongated contact portionsresiliently biased toward one another, each contact portion having afixed end and a free end with the free ends of the two portions beingopposite, each contact portion carrying two spaced contacts which facethe contacts of the other contact portion to present two spaced pair ofcontacts each of which is adapted to open and close, closing of eitherpair of contacts serving to complete an electrical circuit between theterminals regardless of whether the other contact pair is closed; anactuating arm pivotally mounted in the case and carrying a cam whichextends between the contact portions between the contact pairs, the armbeing pivotal between a first position in which the cam engages andholds the contact portions apart to open both pairs of contacts and asecond position in which the cam is not in operative engagement with thecontact portions so that both contact pairs are free to close, the armbeing adapted to be mechanically engaged by an operator to be pivotedtoward one of said positions; and bias means operating against the armto urge it toward the other of said positions.

2. A switch according to claim 1 wherein the arm has an inner end atwhich it is pivotally connected to the case; and the cam extendslaterally from the inner end of the arm and pivots coaxially therewith,the cam being bar shaped with its pivotal axis at its midpoint; and thecontact portions lie in the plane of pivotal movement of the cam, thefree ends of the two portions being on opposite sides of the cam, thecam being parallel to the contact portions when the arm is in saidsecond position and transverse to the contact portions when the arm isin said first position, the opposite ends of the cam engaging respectivecontact portions as the arm moves toward said first position to causethem to be flexed in opposite directions about their fixed ends.

3. A switch according to claim 2 wherein the contact portions are offsetapart between the contact pairs to receive the cam.

4. A switch according to claim 2 wherein the arm extends outwardly ofthe case; and there are two abutments on the case on opposite sides ofthe arm and the bias means comprises a compression spring adapted to beseated between either abutment and the arm.

5. In a switch the combination comprising:

a first electrically conductive, elongated leaf with an anchored endfrom which the leaf extends and which is pivotal about the anchored end,said leaf being adapted for connection in an electrical circuit;

a second electrically conductive, elongated leaf with a substantialportion of the length thereof in overlapping, facing relation to saidfirst leaf and having an anchored end disposed at the side of the facingportions of the leaves opposite the side on which the anchored end ofthe first leaf is located, said second leaf being pivotal about itsanchored end and being adapted for connection in an electrical circuit;

said first and second leaves being resiliently biased to urge theoverlapping portions toward one another;

a set of two contacts mounted on and spaced along the length of thefirst leaf which face the second leaf;

a second set of two contacts mounted on and spaced along the length ofthe second leaf which each face a contact of the first set, to therebyestablish two pair of facing contacts with the contacts of a pairmovable toward and away from engagement with one another;

said contacts when in engagement providing a space between said leavesthat is also between the two contacts of each set; and

a double ended operating cam disposed between the 10 References CitedUNITED STATES PATENTS 2,641,663 6/1953 Krieger 2006 X 2,903,531 9/1959Winter ZOO-453.1 X

FOREIGN PATENTS 142,575 1/ 1931 Switzerland. 1,332,034 6/ 1963 France.

ROBERT K. SCHAEFER, Primary Examiner.

H. BURKS, Assistant Examiner.

